Effect of feed condition on thrust force and torque during continuous and step-by-step drilling of cortical bone

Abstract

Abstract Chip evacuation is one of the fundamental difficulties during continuous drilling of the cortical bone. As the drilling process progresses, discontinuous chips tend to cluster together and clog the drill flutes, which can result in increased temperature, poor hole quality, elevated thrust force and torque, and can even cause the drill bit to break. In this study, continuous and step-by-step drilling processes of the cortical bone were conducted to investigate the thrust force and torque using experimental and numerical modeling methods. By using the finite element method, an elastic–plastic constitutive model was employed to predict the thrust force and torque experienced during bone drilling, and a series of drilling tests was conducted. The experimental results showed a significant increase in the thrust force and torque owing to the chip clogging during the continuous drilling process while this increase was not observed in the simulations. It was shown that the step-by-step drilling method can reduce the increased thrust force and torque during the drilling of cortical bone, and the numerical results of this drilling process were demonstrated to be consistent with the experimental ones. The reduced thrust force and torque indicated that the chip clogging may be reduced by using the step-by-step drilling method, and the numerical results suggested that the finite element model can be used to assist surgeons in selecting drilling conditions to control the process in step-by-step drilling of the cortical bone.